This proposed study represents an extension of two successful NIH-funded research programs on improving effectiveness of mass media risk reduction campaigns and on developing school- and media-based HIV prevention strategies at that reduce the sexual risk-taking behavior of individuals predisposed to high levels of risk-taking. This study will provide a stringent and externally valid test of highly promising strategies for increasing the persuasive effectiveness of television and radio public service announcements (PSAs) in the arena of HIV and other STI prevention. These strategies revolve around the effective design and targeting of PSAs to reach individuals who are high sensation seekers and/or are impulsive decision-makers. Sensation seeking, a trait characterized by novelty seeking and risk taking, is related to use of a variety of risk-taking behaviors and is related to distinct preferences for novel and arousing messages. Impulsive decision-making, a trait characterized by high levels of disinhibition and affective as opposed to cognitive processing, has also been found to be related to sexual risk-taking in a variety of ways. This study will examine the effectiveness of intensive radio and television campaigns in persuading young adults to increase condom use. It will involve a field experiment in two comparable top 75 Nielsen markets and will employ an innovative and methodologically rigorous controlled time-series design. The study will employ 3 high saturation 3-month TV and radio PSA campaigns(2 in one community and 1 in the other) focusing on condom use, with extensive pre- and post-campaign periods. Over the 33-month assessment period, the study will monitor PSA exposure, condom use, condom use attitudes, self-efficacy, perceived norms, intentions, as well as individual difference variables (particularly sensation seeking and impulsive decision- making), through interviews with monthly random samples from young adult cohorts in the two communities. The principal objectives of the study are: 1) to test the ability of a combined television and radio PSA prevention campaign, employing new and promising strategies for targeting, formative research, message design, and placement, to reach at-risk young adults with HIV and other STI prevention messages (i.e., focusing on safer sex); 2) to provide a controlled longitudinal test of the ability of such a campaign to produce significant changes in attitudes, beliefs, self-efficacy, perceived norms, and behaviors related to sexual risk-taking; 3) to explore the ability of a booster (or follow- up) campaign to enhance or sustain the impact of a previous campaign; and 4) to explore the roles of sensation seeking and impulsive decision-making in mediating the effects of HIV and other STI-related PSAs on condom-related attitudes, beliefs, self-efficacy, perceived norms, and behaviors.